Additional value of whole-body positron emission tomography with fluorine-18-2-fluoro-2-deoxy-D-glucose in recurrent colorectal cancer.
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PURPOSE: To assess the additional value of the whole-body [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scan as a staging modality complementing conventional diagnostic methods (CDM) in patients suspected of having recurrent colorectal adenocarcinoma. PATIENTS AND METHODS: In 103 patients, the discordances between FDG-PET and CDM results were identified and related to the final diagnosis obtained by histopathology or clinical follow-up (> 1 year). All FDG-PET studies were reviewed with full knowledge of the CDM findings. RESULTS: In a region-based analysis, discordances between CDM and FDG-PET findings were found in 40 of 412 regions (10%). In these, FDG-PET had additional diagnostic value in 14 of 16 locoregional, six of seven hepatic, seven of eight abdominal, and eight of nine extra-abdominal regions. In a patient-based analysis, CDM categorized a subgroup of 60 patients as having resectable recurrent disease limited to the liver (n = 37) or locoregional region (n = 23). In 13 of these patients, there were discordant FDG-PET findings, detecting additional tumor sites in nine patients and excluding disease in three patients and yielding an additional diagnostic value in 20% of the patients. A second subgroup consisted of 13 patients with inconclusive CDM findings (n = 5) or with elevated plasma carcinoembryonic antigen levels and an otherwise negative conventional work-up (n = 8). In these patients, FDG-PET results were correct in eight of nine discordances, yielding a positive additional diagnostic value in 62% of the patients. CONCLUSION: Whole-body FDG-PET can have a clear impact on the therapeutic management in the follow-up of patients with colorectal cancer. (+info)
Evaluation of dopaminergic presynaptic integrity: 6-[18F]fluoro-L-dopa versus 6-[18F]fluoro-L-m-tyrosine.
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The effectiveness of 6-[18F]fluoro-L-m-tyrosine (6FMT) to evaluate dopamine presynaptic integrity was compared to that of 6-[18F]fluoro-L-dopa (6FDOPA) in vivo by positron emission tomography (PET). Six normal and six 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned monkeys received 6FDOPA and 6FMT PET scans on separate occasions with identical scanning protocols. Four measures, the rate of uptake of tracer into striatum using either the arterial input function (Ki) or the activity in the occipital cortex as the input function (Kc), the rate of loss of striatal radioactivity (k(loss)), and an index of "effective turnover" of dopamine (k(loss)/Ki), were obtained for both tracers during extended PET studies. 6-[18F]Fluoro-L-m-tyrosine was as effective as 6FDOPA in separating normals from MPTP-lesioned subjects on the basis of the uptake rate constants Ki and Kc. However, in contrast to 6FDOPA, it was not possible to differentiate the normal from the lesioned animal using k(loss) or k(loss)/Ki for 6FMT. Thus, FMT appears to be a reasonable, highly specific tracer for studying the activity of aromatic dopa decarboxylase enzyme as an index of presynaptic integrity. However, if one is interested in investigating further the metabolic pathway and obtaining an in vivo estimate of the effective turnover of dopamine (after pharmacologic manipulation, for example), 6FDOPA remains the tracer of choice. (+info)
18F alpha-methyl tyrosine PET studies in patients with brain tumors.
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We have developed 18F-labeled alpha-methyl tyrosine (FMT) for PET imaging. The aim of this study was to evaluate the clinical application potential of FMT for patients with brain tumors. METHODS: Eleven healthy volunteers and 20 patients with brain tumors were injected with 185 MBq (5 mCi) FMT. In 3 healthy volunteers, whole-body imaging and urinary and plasma analysis were conducted for the assessment of the biodistribution of FMT. The normal range of cortical standardized uptake value (SUV) as a reference for comparing tumor SUV of FMT was estimated by using PET data obtained at 30 min postinjection in 8 healthy volunteers. Dynamic PET scans were conducted for 100 min in 4 healthy volunteers and for 30 min in 15 patients with brain tumors. The 10-min static images in another 4 volunteers and all patients were obtained at 30 min postinjection. In 13 patients, FMT uptake in the brain tumor was compared with 18F-fluorodeoxyglucose (FDG). Tumor-to-normal cortex count (T/N) ratio and tumor-to-white matter count (T/W) ratio and SUVs of brain tumors were determined on FMT and FDG PET images. RESULTS: Approximately 1480 MBq (40 mCi) FMT were produced in one radiosynthesis. Percentage injected dose (%ID) of FMT in the brain ranged from 2.8% to 4.9%, and approximately 50%ID of FMT was excreted in urine during 60 min postinjection, of which 86.6% was unmetabolized FMT. A faint physiological brain uptake with SUV of 1.61 +/- 0.32 (mean +/- SD, n = 8) was observed in healthy volunteers. Tumor SUV of FMT ranged from 1.2 to 8.2, with mean value of 2.83 +/- 1.57 (n = 23), which was significantly higher than that of the cortical area in healthy volunteers (P < 0.01). T/N and T/W ratios of FMT were significantly higher than those of FDG (2.53 +/- 1.31 versus 1.32 +/- 1.46, P < 0.001; 3.99 +/- 2.10 versus 1.39 +/- 0.65, P < 0.0001, respectively). CONCLUSION: FMT, like other radiolabeled amino acids, can provide high-contrast PET images of brain tumors. (+info)
Glucose transporters and FDG uptake in untreated primary human non-small cell lung cancer.
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PET imaging of malignant tumors with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) as a tracer is a noninvasive diagnostic and prognostic tool that measures tumor metabolism. In this study, we assessed the relationships between FDG uptake and the expression of facilitative glucose transporters, the sizes of populations of proliferating cells and infiltrating macrophages in patients with primary non-small cell lung cancers (NSCLC). METHODS: FDG uptake and the expression of five glucose transporters and the proportions of proliferating cell and macrophage populations were studied in paraffin sections from untreated primary lung cancers by immunohistochemistry. The patients were imaged with FDG PET before surgery. RESULTS: All tumors could be detected by FDG PET. Uptake was correlated with tumor size (P = 0.004). FDG uptake was lower in adenocarcinomas (ACs) than in squamous cell carcinomas (SQCs) (P = 0.03) or large cell carcinomas (P = 0.002) [standardized uptake value corrected for lean body mass (SUL) = 5.42 +/- 2.77, 8.04 +/-3.25 and 10.42 +/- 4.54, respectively]. Glut-1 expression was significantly higher than that of any other transporter. All tumors tested (n = 23) were Glut-1-positive (70.8% +/- 26.1% of tumor cell area was positive and staining intensity was 2.8 +/- 1.2). Glut-1 expression was higher in SQCs (78% +/- 17.8% and 3.5 +/-0.6) than in ACs (47.5% +/- 30.3% and 1.6 +/- 1.1; P = 0.044 for positive tumor cell area and P = 0.005 for staining intensity). Proliferating cells constituted 15.3% +/- 13.1% of the cancer cells, and the average number of macrophages was 7.8% +/- 6.3%; neither correlated with FDG uptake. CONCLUSION: In this population of patients with NSCLC, Glut-1 is the major glucose transporter expressed. Both FDG uptake and Glut-1 expression appear to be associated with tumor size. No association was found between FDG uptake and either macrophage or proliferative cell populations. (+info)
Feasibility of fluorodeoxyglucose dual-head gamma camera coincidence imaging in the evaluation of lung cancer: comparison with FDG PET.
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The purpose of this study was to elucidate the feasibility of fluorodeoxyglucose gamma camera coincidence imaging (FDG GCI) in the evaluation of lung cancer in comparison with FDG PET. METHODS: Twenty-three patients with recently diagnosed lung cancer were examined with both FDG PET and FDG GCI on the same day. Pulmonary lesions were analyzed visually and semiquantitatively using the ratio of lesion-to-background counts (L/B ratio). The L/B ratio of FDG PET without attenuation correction (AC) was also calculated and compared. Nodal stations were only visually analyzed. RESULTS: FDG GCI and FDG PET could detect 22 and 23, respectively, of 23 pulmonary lesions by visual analysis (95.7% versus 100%). The L/B ratio of FDG GCI was 4.26 +/- 2.55, and significantly lower than that of FDG PET (9.29 +/- 4.95; P < 0.01). The L/B ratio of FDG PET was significantly higher with AC than that without AC (9.29 +/- 4.95 vs. 6.66 +/- 4.65; P < 0.01). When the L/B ratio threshold was set at 5.0 for FDG PET and 2.7 for FDG GCI, their sensitivity was 87.0% and 73.9%, respectively. Of the 3 and 6 patients with false-negative results on semiquantitative analysis, the lesions in 3 patients on FDG PET and 4 patients on FDG GCI were less than or equal to 2.0 cm in greatest diameter, respectively. In the assessment of mediastinal involvement, FDG PET was 77.8% sensitive, 78.6% specific and 78.3% accurate, whereas FDG GCI was 77.8% sensitive, 92.9% specific and 87.0% accurate. In the hilar regions, FDG PET was 100% sensitive, 84.2% specific and 87.0% accurate, whereas FDG GCI was 75.0% sensitive, 89.5% specific and 87.0% accurate. CONCLUSION: In this study, FDG GCI yielded results comparable to FDG PET on visual analysis to detect pulmonary lesions and lymph node metastases. However, the lesion-to-background contrasts of pulmonary lesions and nodal involvement were lower in FDG GCI than in FDG PET. Comparison between the L/B ratio of FDG PET with and without AC indicated that, with AC, FDG GCI would be closer to FDG PET in the evaluation of lung cancer. (+info)
Assessment of pulmonary lesions with 18F-fluorodeoxyglucose positron imaging using coincidence mode gamma cameras.
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Accurate assessment of lung carcinoma remains a significant clinical problem, often leading to surgical procedures without curative potential. PET with 18F-fluorodeoxyglucose (FDG) has shown promise in differentiating benign from malignant lesions and in staging the extent of disease, resulting in improved treatment at a significant cost savings. This multicenter prospective study used dual-detector coincidence imaging with FDG to categorize pulmonary lesions as benign or malignant. The goal of this study was to determine the sensitivity and specificity of dual-detector coincidence imaging of FDG in patients with pulmonary lesions who were scheduled to have a diagnostic procedure for histopathologic confirmation. METHODS: A total of 96 patients with pulmonary lesions with a lesion size ranging from 1 to 7 cm with a mean of 3.44 cm based on their chest radiograph or CT scan were studied using FDG scans with a dual-detector coincidence detection system. An additional 24 patients were entered as control subjects. The studies of 120 subjects were interpreted in random order by three physicians experienced in the use of FDG in patients with lung cancer. Surgical pathology was used as the standard for identifying malignant lesions. RESULTS: There was 94% agreement between the readers in the independent interpretation of the FDG studies. In the 96 patients with pulmonary lesions, FDG studies were 97% sensitive and 80% specific in identifying proven malignant lesions. CONCLUSION: The results of this prospective study provide evidence that dual-detector coincidence imaging with FDG provides an accurate, sensitive and specific means of diagnosing malignancy in patients with pulmonary lesions. (+info)
Oncological applications of FDG PET imaging: brain tumors, colorectal cancer, lymphoma and melanoma.
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This article will focus primarily on body oncology diagnosis, staging and therapy monitoring using fluorodeoxyglucose (FDG) PET imaging. Common pitfalls and artifacts in body FDG imaging will be covered. Examples of diagnosis, staging and therapy monitoring of brain tumor, colorectal cancer, lymphoma and melanoma will be given. Importance of correlation with anatomic imaging and practical use of FDG imaging in patient management will be stressed. (+info)
Measuring reproducibility of regional brain metabolic responses to lorazepam using statistical parametric maps.
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Statistical parametric mapping (SPM) is a method for localizing differences in brain activation patterns without the need for anatomic predefined constraints. The purpose of this study was to assess the reproducibility of the patterns of activation obtained with SPM for baseline measures and for metabolic changes in response to lorazepam on a test-retest design. The results were compared with those we previously published using region-of-interest (ROI) methods. METHODS: Sixteen healthy right-handed men were scanned twice with PET and [18F]fluorodeoxyglucose (FDG): before placebo and before lorazepam (30 microg/kg). The same double FDG procedure was repeated 6-8 wk later to assess test-retest reproducibility. Image datasets were analyzed by using SPM95 software. Difference images between baseline and lorazepam were compared for the first and second evaluations, both for relative decreases as well as increases in metabolism. Significance level was systematically varied to P < 0.001, P < 0.01 and P < 0.05. RESULTS: There were no differences in the baseline SPM maps obtained for the first and second evaluations. SPM showed similar, although not identical, differences in response to lorazepam between the two evaluations. Both evaluations showed significant decreases in occipital cortex (9.7% and 10%) and significant relative increases in left temporal pole (6.8% and 10.4%). However, the second evaluation showed a decrease in the left frontal cortex (areas 6 and 8), which was not present in the first evaluation. The results were very similar to those we had obtained with ROI methods, except for the activation in the left temporal pole, which we had not observed with ROI analyses. CONCLUSION: Although the overall pattern of lorazepam-induced activation depicted by SPM was reproducible in pattern and magnitude, there were some differences that included a left frontal area of deactivation during the second but not the first evaluation. Results with SPM are similar to those with the ROI method, and, because it systematically analyses the whole brain, SPM can uncover patterns not seen with the ROI method. (+info)